Embryo transfer (ET) procedures have gained widespread usage in modern human and animal programs of assisted reproduction. However, to optimize ET success rates, an objective test is needed to accurately determine the viability of individual preimplantation embryos: l) following embryo collection, 2) after conducting various procedures of assisted reproduction (IVM/IVF/cryopreservation), and 3) prior to transfer to a synchronized recipient. The short-term goal of the Phase I SBIR proposal is to design, produce and test a portable, high-resolution, prototype system that is capable of performing a rapid, non-invasive assessment of the viability of a single mammalian embryo in vitro. Our working hypothesis states that embryo oxygen consumption (QO2 = respiration) is a direct measure of that embryo's potential to survive in vivo following ET. The future potential of this research is to commercialize a novel, high- resolution, micro-respiration apparatus that is capable of predicting the "viability" of an individual oocyte/embryo. By directly testing the sensitivity, resolution and user-friendly nature of this technology, results of this Phase I project will define the applicability of the technology, and will provide the necessary technical basis to support a Phase II application to further modify and field-test the "embryo viability system" for commercialization.